Coes was a Greek military commander of Mytilene. He supported King Darius Hystaspes of Persia in his Scythian expedition as commander of the Mytilenaeans. Coes dissuaded the king from breaking up his bridge of boats over the Danube, and so cutting off his own retreat. For this good counsel, he was appointed by Darius on his return as the new tyrant of Mytilene.